The prevention effect of poly (l-glutamic acid)/chitosan on spinal epidural fibrosis and peridural adhesion in the post-laminectomy rabbit model

Purpose

Spinal epidural fibrosis and adhesion are implicated as one of the key factors of failed back surgery syndrome, which may cause dura mater compression or peridural tethering, resulting in persistent backache and leg pain. Various materials or drugs have been used to inhibit formation of epidural fibrosis and reduce the compressive effect on neural structures. Nevertheless, the effects are not satisfied. In this study, we investigated the prevention effect of poly (l-glutamic acid)/chitosan (PLGA/CS) barrier on epidural fibrosis developing post-laminectomy in a rabbit model.

Methods

Sixteen rabbits were divided randomly into two equal groups: group A (experimental group, n = 8) and group B (non-treatment group, n = 8). In both groups, total L5–6 laminectomy was performed; further both ligamentum flavum and epidural fat were removed gently. In experimental group, the laminectomy sites were treated with PLGA/CS barriers, while no additional treatment was received in non-treatment group. At 1, 12 and 24 weeks post-surgery, the animals were subjected to magnetic resonance imaging (MRI) evaluation. Following last MRI examination, all rabbits were sacrificed and their spinal columns were totally removed for further macroscopic and histological evaluation.

Results

MRI showed that rabbits treated with PLGA/CS barrier at 12 and 24 weeks post-surgery had less epidural fibrosis or scar tissue, peridural adhesion, foreign body reaction and low pressure of spinal cord in comparison with the non-treatment group. In consistence with the radiographic results, macroscopic analysis and histological examination showed that the amount of scar tissue and the extent of epidural adhesion decreased significantly in experimental groups. Concerning the fibroblast density evaluated, the scores were significantly lower in experimental group compared with those in non-treatment group.

Conclusion

The results of our study demonstrate that PLGA/CS barrier is effective in inhibiting epidural fibrosis and peridural adhesions in post-laminectomy rabbit model.     

Effects of sodium hyaluronate on peridural fibrosis after lumbar laminotomy and discectomy

Sodium hyaluronate, 1.9% solution, was evaluated for its ability to retard peridural fibrosis after unilateral lumbar hemilaminotomy, anular fenestration, and nuclectomy in dogs. Three materials: fat grafts, gelfoam, and sodium hyaluronate, were compared with empty controls for their ability to inhibit peridural fibrosis. Each dog served as his own internal control and the formation of fibrosis was evaluated at 2, 4, 12, and 26 weeks. Sodium hyaluronate was found to inhibit fibrosis more than the other materials on both a macroscopic and microscopic level. The area of fibrosis and tenacity of the adhesions on dissection were notably less in the sodium hyaluronate group. Microscopically, the thickness of collagen and number of fibroblasts were decreased with the use of 1.9% sodium hyaluronate. The peridural fibrosis occurred equally both anteriorly and posteriorly to the nerve roots and correlated with the area of surgical dissection. Fat grafts were not effective in preventing fibrosis anteriorly, especially in the region of the exiting nerve roots. Gelfoam did not inhibit but actually appeared to increase fibrosis formation. Interposition materials currently used in humans to prevent scar formation such as gelfoam and fat grafts have only addressed the posterior scar formation, which do little to alter the fibrosis anteriorly. The adhesions between the nerve root and the anulus fibrosus bind the nerve root down anteriorly, making it more vulnerable to recurrent disc herniation. Sodium hyaluronate, 1.9% solution, with its viscous semifluid properties, coats the nerve roots and dura anteriorly and posteriorly.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inhibition of peridural fibrosis after laminectomy using low-dose external beam radiation in a dog model

OBJECTIVE: Clinical studies have demonstrated a significant association between the presence of extensive postlumbar discectomy peridural scar formation and the recurrence of low back and radicular pain. Low-dose perioperative radiation therapy has previously been demonstrated to inhibit peridural fibrosis after laminectomy in a rat model. The current study was designed to measure the effect of low-dose radiation on postlaminectomy peridural fibrosis development in a larger animal model. METHODS: Three dogs underwent a total of 12 lumbar hemilaminectomies. For each animal, two levels received 1) external beam radiation 24 hours before surgery, 2) surgery alone, or 3) radiation alone. Radiation was administered in a single fraction of 700 cGy using computed tomographic guidance for dosimetry planning. The isodose distribution was such that the dose conformed to the posterior epidural space with minimal exit dose to normal tissue. Port films were used to confirm the correct levels. Gadolinium-enhanced magnetic resonance imaging (MRI) of the lumbar spines was obtained before the animals were killed 12 weeks after surgery. The spines were harvested, and axial sections through the laminectomy defect were stained with hematoxylin and eosin and Masson's trichrome. All specimens were evaluated for extent of fibrosis along the dura, density of fibrosis, nerve root entrapment, and sublaminar fibrosis. RESULTS: There were no complications from the surgery, and no new neurological deficits were noted. There was a statistically significant difference between the irradiated and nonirradiated groups regarding the extent of fibrosis (P = 0.001) and the density of fibroblasts (P = 0.001). There was also a marked difference in nerve root entrapment (P = 0.182) and the presence of sublaminar fibrosis (P = 0.061) between the treatment and control groups. MRI revealed less gadolinium enhancement at the irradiated levels compared with the nonirradiated levels, confirming the usefulness of MRI in predicting the degree of epidural fibrosis. CONCLUSION: Low-dose external beam radiation therapy administered 24 hours before laminectomy in a dog model significantly decreased the extent and density of peridural fibrosis as well as nerve root entrapment and sublaminar fibrosis. This treatment strategy may be efficacious in patients with recurrent radicular pain after lumbar discectomy that is thought to be secondary to peridural fibrosis on the basis of gadolinium-enhanced MRI studies, and who might benefit from reoperation for nerve root decompression.     

The influence of vertebral instability on peridural circulation and concomitant peridural fibrosis formation

An animal model of vertebral instability was used to analyze the effect of chronic lumbar instability on the peridural vasculature and fibrosis formation. Fifty mature male domestic rabbits were divided into five equal groups. The vertebral instability was performed by excision of supra and interspinous ligaments between L2-L3 and L3-L4, excision of transverse and spinous processes and making bilateral laminectomies and facetectomies in groups I, II, III and IV. In group V only para vertebral muscle dissection was performed without vertebral instability. The simulation of the long term effects of overuse model on unstable spines (chronic instability) were performed with the use of Electrical Neuromuscular Stimulator to simulate cyclic flexion–extension movement in groups I, II. The rabbits in group I and III were sacrified for the histological evaluation at postoperative fifth day. The rabbits in groups I II, IV and V were sacrified at postoperative 21st day. There was no peridural venous endothelial injury or stasis but there was an increased amount of polymorph nuclear leukocytes in both group I (unstable-overuse) and group III (unstable-no overuse) after sacrification at postoperative fifth day. Peridural fibrosis and also vascular changes with different grades were seen in group II, VI and V after sacrification at postoperative 21th day. The grade of the venous changes and the mean amount of peridural scar formation were prominently higher in group II (unstable-overuse) than in group IV (unstable-no overuse) and V (control group). There was no difference between group IV and V for peridural scar formation and vascular changes. In conclusion, the instability of the lumbar spine with overuse could be a cause of peridural venous circulatory impairment, resulting in fibrosis formation.     

Expanded polytetrafluoroethylene membrane for the prevention of peridural fibrosis after spinal surgery: an experimental study

One of the most common complications of lumbar spine surgery is peridural fibrosis, a fibroblastic invasion of the nerve roots and the peridural sac exposed at operation. Peridural fibrosis may produce symptoms similar to those the patient experienced preoperatively and, if another spinal operation is necessary, may increase the risk of injury at re-exposure. In a controlled study in dogs, we assessed the use of expanded polytetrafluoroethylene (ePTFE) as a barrier to postoperative invasion of fibrous tissue into the laminectomy defect. In 14 dogs, a two-level laminectomy was done, at L4-L5 and L6-L7. In 12 dogs, an ePTFE membrane was placed directly over the dorsal surface of the laminectomy defect at L4-L5 and within the defect (over the surface of the dura) at L6-L7. No material was implanted in two dogs (controls). Tissue for histologic studies was obtained from the controls and from ten dogs with the membrane 12 weeks postoperatively. Two dogs with the membrane underwent reoperation. The study found that there was no peridural fibrosis in seven of the ten specimens in which the ePTFE membrane had been placed directly on the dorsal surface of the laminectomy defect, some peridural fibrosis in all specimens in which the membrane had been placed within the defect, and extensive fibrosis in controls. The ePTFE membrane created an excellent plane of dissection for reoperation. No foreign-body reactions to the membrane or membrane-related infections occurred. We conclude that the ePTFE spinal membrane, when properly implanted, is an effective barrier to postsurgical fibrous invasion of the vertebral canal. Clinical studies of use of this material in spinal surgery are warranted. Received: 24 November 1997 Revised: 26 November 1998 Accepted: 2 December 1998     

透明质酸钠预防术后硬膜外粘连的组织学和超微结构研究

为了探讨透明质酸钠预防椎板切除后硬膜外粘连机理，本研究采用高分子量（１．５×１０６）透明质酸钠作实验植入材料，使用兔非相邻节段椎板切除动物模型进行实验研究。３０只兔共６０个节段随机分成两组，⑴２％透明质酸钠组；⑵生理盐水对照组。术后２、４、６、８周处死动物取材，分别做光镜、扫描电镜、透视电镜检查。结果表明：高分子透明质酸钠具有明显预防术后硬膜外粘连的效果。它具有屏障作用，能抑制成纤维细胞、炎性细胞的渗出，是预防硬膜外粘连的良好材料     

A comparison of the effectiveness of mitomycin C and 5-fluorouracil in the prevention of peridural adhesion after laminectomy

OBJECT: The effectiveness of the topical application of mitomycin C (MMC) or 5-fluorouracil (5FU) in preventing peridural adhesion after laminectomy was compared in this study. METHODS: Laminectomies were performed at L-1 in 30 rats. Cotton pads soaked with 0.1 mg/ml MMC, 25 mg/ml 5FU, or 9 mg/ml saline (control) were applied to the operative sites. To evaluate neurological deficits pre- and postoperatively, somatosensory evoked potentials were monitored and the Basso-Beattie-Bresnahan locomotion test was performed. Four weeks postlaminectomy the rats were killed, and peridural scar adhesion was evaluated histologically. The level of hydroxyproline, the area of peridural scar tissue, and the number of fibroblasts were determined. The degree of peridural adhesion was classified according to the Rydell standard. RESULTS: No obvious adhesion formed in the rats in the MMC group, but severe peridural adhesions were found in those in the 5FU and control groups. The content of hydroxyproline, the area of peridural scar tissue, and the number of fibroblasts in the MMC group were significantly lower than those in the 5FU and control groups. CONCLUSIONS: The topical application of MMC rather than 5FU may be a successful method of preventing postlaminectomy peridural adhesions.     

ADCON®-L: a review of its development,mechanism of action,and preclinical data

ADCON^®-L Anti-Adhesion Barrier Gel is a resorbable gel that is placed into the site of a laminectomy before surgical closure and acts as a barrier to scar and surgical adhesions. The scientific rationale for ADCON products is based on certain properties of glial cells and the nature and role of the basal lamina. ADCON-L was evaluated in laminectomy models using rats and rabbits and a discectomy model in dogs. In all studies, ADCON-L was an effective barrier to peridural scar and surgical adhesions.This study was supported by Gilatech Inc.     

Evaluation of hyaluronic acid sheet for the prevention of postlaminectomy adhesions.

BACKGROUND CONTEXT: Various materials have been tested for their ability to maintain a barrier between muscles and epidural space in order to physically or chemically inhibit scar ingrowths. Hyaluronic acid (HA) solution and gel have been reported to be effective in preventing adhesions postlaminectomy; however, neither has been used clinically after spinal surgery. PURPOSE: To determine the efficacy of HA sheet for the prevention of postlaminectomy adhesions compared with that of HA gel or another sheet. STUDY DESIGN/SETTING: An animal model of lumbar laminectomy in rabbits was used to study postoperative scar tissue formation around the spinal cord. The histologic effects of HA sheet were compared with those of Gelfoam (GF) and further evaluated by an inflammation model using rhTNF-alpha. PATIENT SAMPLE: Rabbit. OUTCOME MEASURES: Histologic examination. METHODS: Five rabbits were killed at 2, 4, 8, and 24 weeks after laminectomy, respectively. Another 18 rabbits were examined in an environment of active inflammation experimentally induced by rhTNF-alpha to compare the effects of HA sheet with those of GF or HA gel. Histologic examination was performed to quantitatively assess invasive scar formation or inflammation postlaminectomy, and then, the histologic effects of HA sheet were compared with those of GF or HA gel. RESULTS: In the HA group, significantly, the area of subarachnoid space was larger, distance from the surface of dura to scar tissues was greater, the number of inflammatory cells in the scar tissues at the site of laminectomy was less, and enlargement of dura was suppressed. Using an inflammation model, we also demonstrated the efficacy of HA sheet treatment. CONCLUSIONS: In an experimental laminectomy model, HA sheet formed a solid interpositional membrane barrier and exhibited anti-inflammatory activity. Further investigations will be needed for HA sheet to be used clinically.     

Expanded polytetrafluoroethylene membrane for the prevention of peridural fibrosis after spinal surgery: a clinical study

Peridural fibrosis developing after laminectomy may cause pain that can necessitate reoperation. Many materials have been used as a barrier to invasion of fibrous tissue into the vertebral canal, but the ideal material has not been found. Various studies in animals have achieved favourable results with an expanded polytetrafluoroethylene (ePTFE) membrane. In a prospective, randomized study, we compared postoperative results in 33 patients who had an ePTFE membrane implanted to cover the defect caused by laminectomy during lumbar spine decompression with the results in 33 patients in whom no material was implanted. At operation, an ePTFE membrane was placed after the decompression procedure to cover the laminectomy defect completely. Systematic clinical and MRI follow-up evaluations of patients with and without the membrane were conducted 3, 6, 12, and 24 months postoperatively. The effect of ePTFE membrane implantation over laminectomy sites on postoperative peridural fibrosis, pain and neurological claudication was assessed. The ePTFE-membrane group had a significantly lower rate of epidural fibrosis on MRI (P < 0.0001) and of clinical manifestations of radiculalgia (P = 0.002) compared with the no-material group. Epidural fibrosis that occurred in the ePTFE group was generally less extensive than that in the no-material group. There was no significant difference in the rate of postoperative claudication in the two groups. Significantly more seromas occurred in the ePTFE group (P = 0.0002). There were no infections or other complications in either group. The results showed that placement of an ePTFE spinal membrane over the laminectomy defect produced by lumbar spine surgery provided a physical barrier to invasion of fibrous tissue into the vertebral canal, and patients with the membrane had less postoperative radicular pain. Received: 24 November 1997 Revised: 26 November 1998 Accepted: 2 December 1998     

Preventing peridural fibrosis with nonsteroidal anti-inflammatory drugs

Peridural fibrosis is one of the more frequent complications of lumbar surgery. Nonsteroidal anti-inflammatory drugs inhibit the inflammatory and fibroblastic response. We performed lumbar laminectomies in 24 rabbits, divided into two groups. The experimental group received 5 mg/kg/day of aceclofenac for 7 days and the control group received 1 cm³ of physiological saline. The samples were stained using immunohistochemical methods. The cellular populations in the inflammatory reaction and the thickness of the fibrous membrane were quantified. The mean of the fibrous area was always less in the rabbits of the experimental group compared to controls (47% less at 2 weeks and 41% less at 4 weeks). We observed an 8% decrease in the number of fibroblasts with antivimentin monoclonal antibodies in the experimental group. In this model, aceclofenac inhibits the presence of inflammatory cells in the fibrous scar in the early stages and reduces the extension of adhesions without adverse reactions.     

Role of peridural fibrosis in the failed back: a review

Failed back surgery syndrome (FBSS) is the presence of persistent, disabling pain in the hip, thigh, leg, or lower back of a patient who has undergone a laminectomy or discectomy. Some degree of FBSS is found in approximately 15% of such patients. There may be a direct relationship between the extent of pathology found during the initial surgical procedure and the probability that FBSS will develop. Although FBSS is usually due to improper diagnosis and surgery, another important cause is peridural fibrosis. Part of the answer may have to do with neuromechanics. In a healthy person, pain associated with dural and nerve root movement does not typically occur when performing activities of daily living. In contrast, in a person with peridural scarring, the dura and nerve roots are bound by fibrosis, and putting traction on the nerve roots and dura by back and limb movement produces pain. This pain is aggravated by the presence of inflammation at the surgical site. Research has shown that disc herniation activates the arachidonic acid cascade, resulting in the production of prostaglandins E₁ and E₂ and leukotriene B, substances that contribute to an inflammatory process that persists after discectomy. In an attempt to inhibit peridural fibrosis, methylprednisolone, polyethylene films, and fat grafts have been applied to the dura after discectomy. These experimental treatments have had limited success. Development of a therapy that reliably prevents peridural adhesive fibrosis will reduce the incidence of FBSS.Sponsored by the University of Tennessee, Memphis, Department of Neurosurgery, and Gliatech Inc., Cleveland, Ohio, USA     

A new material for prevention of epidural fibrosis after laminectomy: oxidized regenerated cellulose (interceed), an absorbable barrier

Epidural fibrosis, which may cause persistent back and leg pain, may develop after laminectomy. Several materials have been used in attempts to minimize epidural fibrosis, with varying results. We evaluated the efficacy of an absorbable cellulose adhesion barrier in preventing epidural fibrosis. In 25 New Zealand white rabbits, laminectomies were performed at L3 and L5 vertebrae. The dura mater was covered by the adhesion barrier (Interceed, TC7, Johnson & Johnson, USA) at L3 laminectomy site (group 1), with L5 laminectomy site serving as an internal control (group 2) in each animal. There was no neurological deficit in any of the animals during the postoperative period. Animals were sacrificed at postoperative day 28. The lumbar spine was removed en bloc and placed in neutral, buffered formalin for 72 h. The specimens were then decalcified and embedded in paraffin. Permanent sections of 5 to 7 microm were stained with hematoxylin and eosin and Masson trichrome dye. Epidural fibrosis was evaluated in a double-blinded manner. The extent of epidural fibrosis was graded as 0, no reaction seen; 1, mild reaction; 2, moderate reaction; 3, extensive reaction, and 4, severe reaction. The histological findings of each group were compared. For the statistical analysis, Wilcoxon signed rank test was used. In group 1, the fibrotic tissue formation was minimal in 19 and moderate in 6 laminectomy sites. In group 2, the fibrotic tissue formation was determined as being extensive in 17 and moderate in 8 laminectomy sites. Statistical analysis showed significant decrease in epidural fibrosis in group 1 (P<0.05). This study showed that Interceed, which is commercially available in the market, especially for abdominal and gynecological surgeries, could be used to prevent epidural fibrosis.     

Use of ADCON®-L to inhibit postoperative peridural fibrosis and related symptoms following lumbar disc surgery: a preliminary report

Study design: This was a prospective, randomized, multicenter, double-blind study. Objectives: The study evaluated the use of ADCON^®-L Anti-Adhesion Barrier Gel to inhibit peridural fibrosis and reduce fibrosis-related symptoms after first-time lumbar discectomy. Summary of background data: Peridural scarring causes tethering of dura and nerve roots, contributing to pain and functional limitation, and that symptoms are evident by 6 months after surgery. Methods: Following discectomy, ADCON-L was applied to patients in the active treatment group. Outcome measures were reduction of peridural scar and postoperative pain. Results: There is an association between peridural scar and recurrent radicular pain. Patients having extensive peridural scar were three times more likely to experience recurrent radicular pain than those patients with less extensive scarring. ADCON-L inhibited peridural scar. Compared to the control group, there was a 23% reduction in the number of patients with extensive peridural scar and a 120% increase in the number of patients having minimal or no scar. ADCON-L reduced the incidence of activity-related pain. There was up to a 50% reduction in the number of patients reporting increased pain while doing typical activities of daily living. Conclusions: ADCON-L is safe, reduces peridural fibrosis, and improves postoperative patient outcome.This study was supported by a grant from Gliatech Inc.     

黄芪预防术后硬膜外粘连的实验研究

目的：探讨黄芪预防术后硬膜外瘢痕粘连的效果。方法：22只新西兰兔行L2和L5节段2椎板切除术,切除部分黄韧带,暴露脂肪,去除硬膜外脂肪,分为两组：A组为黄芪组;B组为生理盐水组,分别在L2和L5椎板缺损区注入黄芪液和生理盐水,术后2、4、8周取材作光镜,透镜观察。结果：黄芪组炎性细胞渗出较少,成纤维细胞较少,胶原纤维形成较少,硬膜外瘢痕无粘连,脊髓和神经根未见变性和脱髓鞘,生理盐水组硬膜外明显。结论：黄芪无神经毒性作用,可作为作一种良好的材料用于预防术后硬膜外瘢痕粘连。     

椎板切除术后早期进行直腿抬高运动对硬膜外纤维化影响的实验研究

[目的]探讨腰椎术后早期进行直腿抬高运动对于硬膜外纤维化的影响。成年新西兰大白兔40只，随机分为2组，全部行S1椎板切除术，实验组于术后模拟人进行直腿抬高运动，而对照组不予任何处理。术后1、2、4、8周每组随机处死5只兔子取材。大体观察1、2周时实验组瘢痕的形成要晚于对照组；4、8周时黏连分级两组存在显著性差异（P〈0．05），实验组重于对照组。2、4、8周时实验组的瘢痕指数高于对照组（P〈0．05）。瘢痕组织学评分1周时两组无差异（P〉0．05），2、4、8周时对照组要优于实验组（P〈0．05）。成纤维细胞及炎性细胞计数，早期实验组细胞数多于对照组（P〈0．05），但晚期两组无显著性差异（P〉0．05）。[结论]腰椎术后直腿抬高运动可增加硬膜外瘢痕的形成，延缓瘢痕的成熟，加重瘢痕对硬膜及神经根的黏连和固定。     

Use of ADCON-L to prevent peridural fibrosis following re-operation for recurrent lumbar radiculopathy: clinical results.

OBJECTIVE: To present the results of a small retrospective study in patients after they have undergone lumbar scar resection and ADCON-L application to prevent recurrent formation of peridural fibrosis. PATIENTS AND METHODS: Between May 1996 and December 1999 nineteen patients underwent surgery for peridural fibrosis. Sixteen patients were eligible for statistical analysis. The mean age was 46.2 years (range 29 to 69 years) and the mean follow-up period was 9.7 months with a range of 3 to 38 months. In 10 patients scar formation was the main factor for nerve root compression. Three out of these patients showed concomitant recurrent disc herniation. Six patients presented with peridural fibrosis but concomitant recurrent disc herniation as the main factor for clinical deterioration. After scar resection and decompression of the nerve roots ADCON-L was applied intraoperatively. RESULTS: Excellent or good results (Prolo score 8 - 10) were achieved in 5 of 16 patients, fair results (Prolo score 6 - 7) in 5 and poor results (Prolo score 2 - 5) in 6 patients. CONCLUSION: ADCON-L may improve the chances of a satisfactory outcome in a small subgroup of patients following scar resection in the postoperative course of lumbar discectomy. Further investigations are necessary to identify clinical and radiographic factors predicting outcome.     

Influence of TachoComb in comparison to local hemostyptic agents on epidural fibrosis in a rat laminectomy model.

This animal experimental study was designed to examine the effects of TachoComb, a fixed combination of collagen with tissue adhesive, as an interposition membrane on the development of spinal epidural fibrosis in comparison to other hemostyptic materials. In 10 Wistar rats, four laminectomies were performed at lumbar and sacral vertebrae. Alternately, a piece of TachoComb, Spongostan, or Tabotamp was placed into each laminectomy site. One laminectomy site served as an empty control (n = 10). 8 weeks later, the animals were sacrificed, and the spinal column including surrounding muscle tissue was removed en bloc from each rat and fixed in formaldehyde. After decalcification and staining the specimens were graded by a neuropathologist in a blindfold test for severity of epidural fibrosis as "light-moderate" or "marked". Epidural scarring of variable density was seen in all laminectomy sites. Light epidural fibrosis, without any adhesion to dura, as only noted in cases after application of TachoComb (n = 4/10) and Spongostan (n = 1/10). All other slices showed marked epidural fibrosis with dura adherence regardless of the implanted material. Statistical analysis revealed significantly lower epidural fibrosis after application of TachoComb compared to all other groups (p < 0.05). In this series, TachoComb is more effective in reducing the epidural fibrosis than Spongostan, and Tabotamp. However, complete prevention of scar tissue formation was not achieved.     

Novel biodegradable lamina for lamina repair and reconstruction

Background contextPosterior laminectomy is an effective spinal surgical procedure. The adhesion of postoperative scar tissue to surgically exposed dura and, occasionally, to nerve roots can cause failed back surgery syndrome. The establishment of a barrier between scar tissue and dura that is made of hard material may prevent scar adhesions.PurposeTo evaluate the efficacy of a novel biodegradable multi-amino acid copolymer/nanohydroxyapatite composite artificial lamina.MethodsA cervical laminectomy animal model in goats was used, and the animals were randomly divided into three groups. In the test group, cervical 4 was removed by laminectomy and the artificial lamina was inserted (n=12). In the control group, the incision was closed directly without implantation (n=9). The goats in the normal group did not undergo any procedure or treatment. Copolymer efficiency was tested by using X-ray, computed tomography scanning, magnetic resonance imaging, scanning electronic microscope, and histologic and biomechanical measurements 4, 12, and 24 weeks postoperation.ResultsNo shifting of the artificial lamina or dural adhesion pressure was observed. New cervical natural bone formed in the defect and the bony spinal canal was rebuilt. In the control group, fibrous scar tissue filled the defect and exerted pressure on the dura. No paralysis was observed, and gait was normal in all test and control goats.ConclusionsArtificial lamina can prevent the epidural adhesions surrounding the defect and promote effectively bone tissue repair and new bone formation.     

自体真皮移植预防硬膜外纤维化及粘连的实验研究

目的 探讨自体真皮移植预防硬膜外纤维化及粘连的效果,为临床应用提供实验依据.方法 选取5头西藏小型猪,手术切除L2、L4全椎板造成缺损,去除硬膜后方硬膜外脂肪暴露硬脊膜,切取自体真皮移植于L2椎板缺损处覆盖硬脊膜(实验组),L4椎板缺损处硬脊膜外不用任何移植物覆盖(自身空白对照组).于术后2、4、6、8、10周全麻下股动脉放血法各处死1头动物,大体观察移植真皮存活情况及是否存在毛发生长、皮脂腺和汗腺分泌物.采用改良Robertson记分法评定硬膜外瘢痕量及粘连程度,SPSS 13.0统计学软件进行统计分析.组织学观察移植真皮内皮肤附属器变化情况.结果 移植真皮全部成活,与体表真皮比较明显增厚(P<0.05).实验组未见移植真皮毛发生长、皮脂腺囊肿和汗液囊肿形成;真皮与硬脊膜之间存在潜在的易分离平面,只有极少量瘢痕组织,粘连疏松,硬膜表面和移植真皮表皮面光滑.对照组大量的瘢痕形成,竖脊肌前方瘢痕组织严重且广泛长人硬膜外腔,与硬脊膜粘连紧密,硬脊膜从瘢痕组织上分离困难.改良Robertson记分法评分,实验组硬膜外瘢痕量及粘连程度明显低于对照组(P<0.05).组织学观察见毛囊萎缩、毛根坏死、皮脂腺及汗腺消失.结论 自体真皮是一种具有良好的抑制瘢痕形成和物理隔离屏障作用的生物材料.自体真皮移植能有效地预防硬膜外纤维化及粘连,具有临床应用价值.